.custom-backtop-icon {
  position: fixed;
  bottom: 40px;
  right: 40px;
  width: 40px;
  height: 40px;
  background-color: #1890ff;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.3s;
}
.backtop{
  left: 1731px;
  top: 974px;
  width: 61px;
  height: 61px;
  opacity: 1;
}
.custom-backtop-icon.show {
  opacity: 1;
}